The present invention is directed to a cable fitting for the protection of a cable connection in a medium voltage technology, wherein strippable cable conductors are connected to a conductive connecting element. The protection of the cable connection is accomplished by a field controlling or shielding element covering the set off edges of the cable conductive layers, a shrinkable inner insulation tube, sleeve or hose disposed on the field controlling element, a shrinkable outer insulation hose, sleeve or tube, a conductive layer and a shrinkable protective hose, sleeve or tube that completely covers the arrangement are arranged lying on top of one another from inside to outside over the joint.
Cable sleeves are notoriously known for the connection of two cables in the medium voltage region. The conductors that are to be connected are respectively contacted with a press or screw connector and are covered with means for controlling the electrical field. Shrinkable insulation hoses or tube are arranged over this means. U.S. Pat. No. 4,383,131, which claims priority from the same British Application as German 29 37 253-C2, discloses such an arrangement. The electrical field control or shield occurs with the help of a heat shrinkable field control tube or shielding sleeve. The outside diameter of this field control tube is smaller than the inside diameter of a shrinkable insulation tube that is to be arranged thereover. Thus, the field control tube or shielding tube overlaps the outside conductor layers of each cable and is not interrupted in its course across the joint. The heat shrinkable insulation tubes that are to be arranged over the field control tube are initially arranged in one another and respectively shrunken following one another onto the field control tube or sleeve, which has already been shrunken on the connection. In order to avoid the individual sleeves getting mixed up or mistaken, these are correspondingly designated or other measures have to be taken, such as diameters that are different from each other, for example. This requires a considerable manufacturing, installation and time outlay. Thus, the field control tubes, for example, are always manufactured smaller in the outside diameter than the insulating tubes or sleeves which are to be arranged thereover. As a result of this pre-customizing, it is then possible to preclude an incorrect insulation in this manner. However, the geometrical adaptation of the tubes and customizing are involved regarding the manufacturing. Potentially, a limitation concerning the shrinking region must be accepted due to the different diameters of the individual sleeves, since the outermost sleeve must be shrunken significantly more than the sleeve that lies inside. Besides, it is disadvantageous that cavities may be formed at the junctions given the utilization of these tubes or sleeves, and these cavities can lead to a partial discharge at the outer conductive layer edges of the cable. An additional band that preferably exhibits field controlling or shielding properties as well was previously utilized at these locations in order to solve such problems. Electrically conductive lacquers, with which the cavities are filled, are also utilized in order to force a defined electrical potential at the described locations and prevent partial discharges therewith.
European 0 681 010-A2 discloses a method for manufacturing a field controlling or shielding layer for medium voltage fittings. This field controlling layer is a liquid polymer with conductive additives of granulated silicon carbide. The mix recipe contains a halogen-free solvent that evaporates after application onto the medium voltage fitting. Such field controlling sealing compounds meet all the required criteria for field controlling layers given medium voltage fittings. Moreover, different exemplary embodiments for the field controlling layer that satisfy the environmental conditions regarding solvents are specified therein, whereby the required electrical conditions are adhered to.